Soaking pit



Nov. 2, 1937. w, MQKEE 2,097,932

' soAxING PIT i Filed larqh 20, 1937 4` sheets-sheet 1 A man I ma w n: l.4:

A'' f A Nmz, 1937. w., MQKEE 2,091,932

SOAKING PIT Filed arch 20. 1937 4 SheetsfSheet 2 55 75' BY, M7-YM MNM 76I ATTORNEYS Novo 2, w. somme PIT4 Filid Ilarch 20, 1937 4 Sheets-Sheet 3INV ENTOR. W /l /5 /VWEE ATTORNEYS Nwz, 1937. w. MOKEE 2,091,932

SOAKING PIT Filed Iaroh 20, 1937 4 Sheets-Sheet 4 ATTORNEYS vPatentedNov. 2, 1937 UNITED STATES PATENT OFFICE SOAKING PIT Willis McKee,Cleveland, Ohio, asslgnor to Central National Bank of ClevelandApplication March 20,1937, Serial No. 132,106

10 Claims. (Cl. 263-9) This invention relates to heating furnaces andmore particularly to an improved soaking pit structure for bringingsteel ingots to the proper heat conditions for rolling.

In the manufacture of steel the molten metal is poured into ingot moldsand the cast ingots are removed from the molds, usually before completesolidication, and placed in heating iurnaces, commonly called soakingpits, wherein the 10 ingots are brought to the proper temperatureconditions for rolling. It is important that all parts of the ingot beat the same temperature when it enters the rolling mill and this isaccomplished by placing the ingot, or a number of ingots, in a heatingchamber where the heat of the mass of the ingots is permitted to becomeequalized throughout and, as necessary, heat is added to bring thetemperature up to the desired value. The usual soaking pit in use todaycom 20 prises a generally rectangular chamber having a sliding cover andconnected to and constructed integrally with checker brick regeneratorsWhereby the air, used in combustion, as well as the fuel ifproducer gasis burned, may be pre-heated.

These soaking pits are expensive to build, require an excessive amountof floor space, and the nature of their design makes it extremelydilcult to obtain satisfactory heating.

There are three conditions that exist `with 30 these pits whichcontribute to the difliculties encountered in'obtaining the bestresults: First, in the old style pit the air and gas are manuallycontrolled so that there is-no way to insure against oxidizing the steelwith excess air, nor

is there any way to insure against the use of excess gas andconsequently the loss of fuel; second, in the old type'of pit the coversare supported on tracks and are designed so that the brick work of thecover comes almost but not quite into contact with the brick work of thepit when the covers are closed. There is, therefore, always an openingand through this opening either the gas is being wasted or air is being.

drawn into the pit thus oxidizing the steel; 45 third, in the orthodoxpit'there are rather large openings in the opposite walls of the pitnear the top and the llame comes in from one side for 15 or 20 minuteswhile the products of vcombustion go out the opposite side and then the50 direction is reversed for the next period. It-is easy to see that theingots will not all be subjected to the same heat conditions from top tobottom and from side to side of the pit.

With Ythe rapid developments in special alloy 55 steel and the morerigid requirements in the is a very eilicient heating furnace.

handling of steel it has become exceedingly important that a soaking pitshould be designed so that it can be completely automaticallycontrolled, and that all parts of all ingots should have the sametreatment. Pits have been designed with sealed covers but it has beennecessary in these pits to remove the whole cover to charge or draw thesteel, necessitating excessive exposure of thesteel, requiring elaboratemechanism for moving the cover, and requiring an excessive amount ofdoor space.

In my improved pit, I use a fuel with a known heat content and I mayconveniently employ standard equipment of well known type to regulatethe heat of the furnace and also to regulate the air and the amount ofgas being used. I admit the air and fuel in a generally tangentialdirection below the hearth of the pit so that the outer 4walls of thepit are heated and the ilame and products of combustion circulate aroundthe pit as they ascend, and nally pass out the openings in the bottom ofthe pit near the center. As my furnace is encased in steel and insulatedand as there is no opening Aor leakage in the top except a small sealedhatch which'is opened 25 only while steel is being actually charged ordrawn,` it will be seen that my improved structure If any preheating ofair andfuel is desired it is preferably done in a separate disconnectedregenerator or recuperator.

Among the objects of my invention is the provision of a soaking pitwherein ingots may be charged and drawn with a minimum of heat loss andof exposure of the steel in the pit to the air. Other objects of myinvention are: the provision of an improved heating furnace or soakingpit for steel ingots in which the necessity for regenerators iseliminated and in which each'ingot is subjected to substantially exactlythe same heating conditions regardless of the position of the ingot inthe heating chamber; the provision of an improved circular soaking pithaving a rotatable cover whereby any ingot may be selectively removedfrom the heating chamber; the provision of a circular soaking pit inwhich the ingots arenot subjected to the direct flame of the heatingburners and are protected-from oxldization: the provision of a circularsoaking pit which is extremely simple in its arrangement andconstruction and which may be provided with a plurality of slag outlets;and the provision of a soaking pit for ingots having a high-heateiliciency and large ingot capacity for a given floor controlled in adenite and accurate manner.

The above and other objects of myinvention will appear from thefollowing description of one embodiment thereof, reference being had tothe accompanying drawings, in which- Figure 1 is a vertical sectionalview through one of my improved soaking pits with the cover and coveroperating mechanism removed. A number of ingots are shown in position.

Figure 2 is a plan View of the apparatus shown in Figure l.

Figure 3 is a fragmentary horizontal section taken on line 3-3 of Figure1 and illustrating the arrangement of the burners in the wall of thepit.

, Figure 4 is a plan view of my improved soaking pit with the cover andcover operating mechanism in place.

Figure 5 is an enlarged fragmentary plan view of the hatch cover liftingand swinging mechanism.

Figure 6 if. an enlarged fragmentary vertical cross-section through mysoaking pit taken on line 6--6 of Figure fl.

Figure 7 is an enlarged detached view of the hatch cover operatingmechanism illustrating the parts in the positions they assume when thehatch cover is closed.

Figure 8 is a view lsimilar to Figure 'i but illustrating the parts inthe positions they assume when the cover has just been lifted.

Figure 9 is a view similar to Figures 'l' and 8 but illustrating theparts in the positions they assume when the cover has been lifted andswung out of registry with the opening in the main pit cover.

`Figure 10 is an end elevation of the apparatus shown in Figure '7.

Referring to the drawings, the main shell of the soaking pit structurecomprises a cylindrical metal drum I having a metal base or bottom 2. Acentrally disposed hollow tubular pintle 3 is rigidly supported on thebase 2 and the entire structure may be supported by suitable columns 4.The bottom of the pit is located suiiiciently above a floor level thatcars may be moved beneath slag outlets 5 and 6 and, if desired, aplurality of my improved soaking pit structures may be arranged in a rowwith their slag outlets in alignment whereby a battery of soaking pitsmay conveniently be served by the same slag cars.

Immediately adjacent-the outer shell I is a lining 1 of heat insulatingmaterial. This lining extends across the bottom of the pit as seen at 8and also surrounds the hollow circular pintle 3 as seen at 9. The restof the interior structure of the soaking pit may be built up of firebrick or other suitable material and comprises a sloping hearth orbottom portion Ill, which is also preferably faced with a.l suitablebottom material such as coke breeze or such other material as may besuitable. 'Ihe pit bottom slopes downwardly from the .central column IIof the brick Work which surrounds the pintle 3 and an annular trough I2extends aro'und the pit bottom at the outer periphery thereof. Thistrough is provided with oppositely disposed slag outlet openings 5 and 6and the trough preferably slopes so that any slag which drains into itwill iiow out of the openings 5 and 6. Any suitable kind of closuremembers, such as the swinging gates I3 and I4, may be provided for theslag outlets 5 and 6 and it will be understood that these are normallykept closed except when it is desired to .space and which may easily andaccurately be discharge slag which has accumulated in the pit or whenmaking bottom.

Above the level of the pit bottom I0 and extending inwardly from theouter wall of the pit I have provided an annular projection I5 having asloping face portion I6 against which the sides of the ingot I1 rest andby whichthey are supported. The gas outlet pipes I8, I9, 20 and 2| areequally spaced around the central column II and extend downwardly intoan annular header conduit 22 which in turn connects to the main flue 23which is adapted to carry the products of combustion to a suitablestack.

A trough 24 extends around the top of the outer wall of the pit and maybe filled with water or sand to provide a seal for the rotating cover aswill be more fully described later. Another trough 25 extends around thecentral metal pintle member 3 and it is also lled with sand or water toseal 'the inner edge of the cover. By providing these annular troughseals the rotatable top or cover, generally indicated at C and best seenin Figure 4, is completely sealed at all times. By this means leakagebetween pit and cover is entirely eliminated and loss of heat greatlyrestricted.

The cover C consists essentially of a suitable frame work built up ofthe main beams 26, the transverse beams 21, a\,circular`outer rim member28 and the inner ring member 29 (see Fig. 6). A body 33, of suitablerefractory and heat insulating material, is supported by the framestructure just described. As seen in Figure 6 a. ange 3| extendsdownwardly from the central ring member 29 into the trough 25 thuscompleting the seal at the center of the cover. In like manner anannular iiange 32 extends downwardly into the outer trough 24 andeffectively seals the outer joint between the cover and the pit. Theentire cover structure is supported by the pintle 3 which has a bearingsupport 33 mounted at its upper end. Thrust bearing 34 carries theweight of the cover and a vertical bushing portion 35, secured in themain transverse beam section 25 of the cover, guides the cover duringits rotation. In order to further insure against undesirable canting ortilting of the cover a plurality of wheels or rollers 36 are mounted atthe outer periphery thereof and may, if the cover should tilt or cantslightly, roll upon the surface 31 formed by an angle member secured tothe outer wall of the trough 24.

The ingots I1 are deposited in the pit in a. vertical position withtheir bases resting on the bottom I0 and their outer sides leaningagainst the inclined face I6 of the projecting portion I5 A plurality oftangentially able fuel, and air are supplied in proper propor tionsthrough the burner nozzles 31 and 38 which are designed andarranged'intimately to mix the fuel and air to insure uniform combustionand the elimination of free oxygen. The gas and air travelingcircumferentially around the pit with the fuel on the inside of the airinsures against the ame coming in contact with the ingots and 76eliminates the possibility of any free oxygen coming in contact with thesteel. As a further precaution, as is clearly seen in Figures 1 and 3,these burners are disposed below the level of the outer edge of the pitbottom l and are adapted to ditangential arrangement of the burnersfurnishes an exceedingly even and uniform distribution of heatthroughout the entire pit and, by providing the outlets for the productsof combustion at the center of the pit structure on the opposite side ofthe ingot from the burners 31, the most emcient utilization of the heatis insured. It will be understood that cooling water pipes, such as thepipe 39 in the projection, I5, may be 'provided wherever necessary ordesirable in the structure.

In order to permit any ingot to be removed from the pit and anotheringot to be inserted in its place without uncovering the entire pit andwithout disturbing any of the other ingots or permitting any substantialloss of heat from the pit, and in order to overcome the necessity forproviding extra floor space to accommodate the pit cover when opened, Iprovide a relatively small` hatchway 40 extending through the top C.This hatchway may be lined with a metal liner 4I,'water cooled ifdesired, having a sand trough 42 in its top for the downwardly dependingflange 43 of the hatch cover 44. As illustrated the cover 44 comprises ametal frame 45 filled in with refractory material and provided with apair of upwardly extending ears 46 having a pin 41 extendingtherebetween.

In the preferred operation of my apparatus the entire top C, includingthe hatchway 40 and the hatch cover 44, is rotated until the hatchway 49is directly above the ingot which is to be removed or above the placewhere an ingot is to be deposited. The hatch cover 44 is then liftedfrom its seat and swung about the center of the pit top C until thehatchway is open whereupon the crane ingot gripping jaws can operate inthe usual manner to deposit or remove an ingot. If desired the top C canbe rotated and the hatch opened simultaneously.

In order to rotate the entire top structure C I provide a relativelylarge stationary gear 48 .which is keyed to the central pintle structure3. A co-acting gear 49 (see Fig. 4) is mounted on and carried by thecover C and may be driven through a suitable gear box 58 by the motor 5Iwhich is also carried by the frame work of the top C. Thus, by drivingthe motor I, the gear 49 will be turned and, as the gear 48 is fixed,the entire cover structure will be rotated about its central support' onthe pintle 3. The cover 44 can, of course, be rotated 'in eitherdirection as desired.

'Ihe hatch cover 44 is lifted and swung in the manner described'above bythe mechanism shown in Figures4 to 8k inclusive. The arm 52 hasa hookedend portion -53 which is disposed between the ears 46 ofthe hatch cover44 and engages the pi'n 41. This arm 52 is split, dividing into twoportions 54.and 55, which are pivotally mounted on a transverse shaft56, and which come together again on the other side of the shaft 6I. Anupwardly extending member 51 provides a support for the cam followerroller 58.

The shaft 56 is supported in the bearing portions 59 and 60 of thebracket member B which in tum is rotatably supported on a vertical shaft8| (seerFig. 6) which extends upwardly from a base member 62-secured tothe frame of the cover C immediately above and in line with the centerof the pintle 3. A thrust flange 63 on the shaft l6I supports thebracket B and thus also supports the weight of the hatch cover 44 whenit is lifted and swung into open position.l By supporting the hatchcover 44 in the manner described it will be -seen that it may be liftedand lowered by moving it with the arm 52 about the shaft 56, and may bemoved out of and into position over the hatch opening 40 by swinging thebracket yB around on the shaft 6I.

The mechanism which accomplishes the lift- V vThe bracket B includes aplatform portion 66 upon which is mounted a reversible motor 61. This'motor is connected to a cam 68 through a vsuitable reduction gear whichmay be housed integrally with the motor. A crank arm 69 is carried bythe cam 66 and has an enlarged head portion 10. The bracket B is alsoprovided with a pair of supporting guides 1| and 12 which guide the rack13 and maintain it -in engagement with thegear segment 64. A connectingrod 15 is pivotally connected at one end to a pin 16 which is secured tothe rack 13 and at its opposite end is shaped to form a socket orreceptacle 11 for the head 10, of the crank arm 69.

Referring particularly to Figures 7, 8,. 9 and l0, the operation of thehatch cover lifting and swinging mechanism will be described.

Assuming that the main soaking pit top or cover C has been rotated untilthe hatch opening 40 'is over the desired portion of the pit and thatthe parts of the hatch cover mechanism are in their hatch-closedpositions as seen in Figure 7, the motor 61 is started and will rotatethe cam 63 in clockwise direction as indicated by the arrow in Figure'7. The follower roller 58 on the short end of the arm 52 will always bein engagement with the cam 68 because of the load imposed cn the arm 52by the weight of the cover 44 and, when the cam 68 rotates through 90into the position shown in Figure 8, the short end of the arm 52 will bedepressed causing the opposite end to be lifted carrying with it thehatch cover 44. As this 90 rotation of the cam 68 takes place the crankarm 69 with its head 18 has moved until the head engages the socket 11in the connecting rod 15. Further rotation of the cam 68 in clockwisedirection to the right will not changethe elevation of the hatch cover44 as the adjacent portion of the cam is of constant radius. However,such movement through an additional 90 will cause the connecting rod 15and the rack 13 Vto be moved into the positions shown in Figure 9. Thismovement of the rack 13, which is maintained in engagement with thefixed gear segment 64 by the guides 1I and 12,

- will result in the arm 52 together with the hatch cover 44 being swungfrom the position shown in full lines in Figure 4 to that shown indotted lines in Figure 4.

When it is desired to re-cover the'hatch open' ing it is'necessary to`reverse the direction of rotation of the motor r61 whereupon the cam 68will move in a counterclockwise direction causing the head 10 of thecrank arm 69 to push against the connecting rod 15, returning the rack13 to the position shown in Figure 7 and return-v ing the arm 52v andthe hatch cover .44 to the positiondirectly above the hatch opening.Fursoy "lov

ther movement of the cam 68 will then permit the arm 52 to return to theposition of Figure rl and the hatch cover to be firmly seated in thesand seal thus eifectively closing the opening in the top of the soakingpit. A stop pin 'i8 retains the connecting rod 15 in position to bepicked up by the crank head 'i0 when the hatch is next opened. A

It will be seen from the above description that the hatch coveroperating mechanism is entirely automatic and is supported entirely uponthe top of the soaking pit.

The hatch cover operating mechanism, and particularly the contourof camS8, may be so designed that the raising and lowering, as well .as therotating motions, are carried out with gradual acceleration andretardation. Again, the vertical and rotating motions of the hatch coverare never simultaneous, one being completed before the other starts.VThe motor 61 may be controlled from a remote point in any suitablemanner. Overruns of the motor 61 can do no harm due to the arrangementof the operating mechanism.

The operation of this improved Vhatch cover mechanism whereby thesoaking pit is opened only through a small opening and for a' minimumtime while charging or drawing an ingot, results in relatively high heatemciency. My insulated circular arrangement of the soaking pit with theburners so disposed that the iiame and products of combustion evenly anduniformly heat all .of the ingots in the pit provides a very simple andtroublejree heating furnace which has low upkeep costs and by which thechecker brick regenerator chambers, blowers, etc. necessary with theusual rectangular soaking pits are eliminated.

By providing the hollow central pintle 3, which supports the entiresoaking pit top structure, a natural draft cooling is obtained whicheectively protects not only the pintle itself but also the operatingmechanism disposed on the top of the cover C. Fin'thermore, this hollowpintle provides readily accessible means for conducting cooling waterpipes, wiring, etc. necessary for the control and operation of the coveroperating mechanism. A minimum of power is required for operating thepit cover because of its roller bearing support upon the pintle and thefact that is may be substantially balanced so that the en- I tire loadis supported on the central pivot. `An effective seal is had at alltimes between the walls of the pit and the rotatingcover andthe entireoperation of the cover may conveniently be effected by remote control.

Although I have described the illustrated embodiment of my invention inconsiderable detail lt will be understood by those skilled in the artthat numerous variations and modications may be made in the apparatusand arrangement of` parts without departing from the spirit of myinvention. I do not, therefore, wish to be limited to the specificembodiment herein shown and described but claim as my invention allforms thereof coming within the scope of the appended claims.

I claim:

1. In a soaking pit or the like having a substantially circular heatingchamber, a central pilaster,

. a top for said heating chamber. having a bearing Von said pilaster androtatable thereabout, said top .having a hatchway opening into theheating chamber, a cover for said hatchway, means for rotating said topabout said pilaster, and means for moving said. cover to open and closesaid hatchway.

aooaose 2. In a heating furnace of the type described having asubstantially circular heating chamber, said heating chamber having adownwardly and outwardly sloping bottom, a trough extending around saidVheating chamber at the outer edge of said sloping bottom, means lfordischarging slag from said trough, a plurality of burners directed intosaid trough and positioned below the top thereof, a tubular centralpilaster having a cooling passage extending therethrough, a gas outletextending downwardly adjacent said pilaster, a rotatable top for saidheating chamber having a bearing on said pilaster and rotatabletherebout, a hatchway in Isaid top and a removable hatch cover for saidhatchway.

3. In a soaking pit of .the type described, walls defining a heatingchamber, a central pintle extending up through said chamber, a top forsaid chamber rotatably mounted on said pintle, said top having ahatchway extending therethrough, a removable cover for said hatchway,means mounted on said top for rotating said top about said pintle andmeans carried by said top for removing and replacing said cover fromsaid hatchway.

4` In a soaking pit of the type described, walls defining a heatingchamber,a central pintle extending up through said chamber, `a top forsaid chamber rotatably mounted on said pintle, said top having ahatchway extending therethrough, a removable cover for said hatchway,means mounted on said top forrotating said top about said pintle andmeans carried by said top for removing and replacing said cover fromsaid hatchway, said last named means including a bracket rotatablysupported on said soaking pit top, an arm pivotally mounted on saidbracket and arranged to lift said cover, a motor mounted on saidbracket, a cam driven by said motor and actuating said arm to lift andlower said cover, a gear fixed to said soaking pit top, a coacting gearcarried by said bracket, and means actuated by said motor for movingsaid gears to cause i said bracket to turn about its support on theiiow, a top supported by said pilaster and means for rotating said topabout said pilaster.

7. In a soaking pit or the like, walls defining a circular heatingchamber, a bottom for said chamber, a trough extending circumferentiallyof the heating chamber at the outer edge of said bottom, a fuelburnerpositioned below the bottom level and adapted to direct products ofcombustion around said trough, an outlet for the products of combustionspaced toward the center of said bottom from said trough, and arotatable top for said heating chamber.

8. In a soaking pit or the like, walls defining a circular heatingchamber, a bottom foi said chamber, a trough extending circumferentiallyof the heating chamber at the outer edge of said bottom, a fu'el burnerpositionedvbelow the bottom level and adapted to direct the ame aroundsaid trough, an outlet for the products of combustion spaced towardthecenter of said bottom from said trough, a rotatable'top for said heatingchamber, said top having a hatchway and a hatch cover, and means carriedby said top for operating said hatch cover.

9. In a soaking pit or the like, walls defining a circular heatingchamber, a bottom for said chamber, a trough extending circumferentiallyof the heating chamber at the outer edge of said bottom, a fuel burnerpositioned below the botlo tom level and adapted to direct the flamearound said trough, an outlet for theproducts of combustion spacedtoward the center of said bottom from said trough, a rotatable top forsaid heating chamber, said top having a hatchway l5 and a hatch cover,meansl carried by said top for operating said hatch cover, andindependent means for rotating said top.

10. In a soaking pit or the like, walls defining a circular heatingchamber, a, bottom for said chamber, a vtrough extendingcircumferentially of the heating chamber at the outer edge of saidbottom, a fuel burner positioned below the bottom level and adapted todirect the flame around said trough, an outlet -for the products ofcombustion spaced toward the center of said bottom from said trough, arotatable top for said heating chamber, said top having a hatchway and ahatch cover, means carried by said top for operating said hatch cover,and independent means for rotating said top, said hatch cover operatingmeans and said top rotatingmeans being adapted to be simultaneouslyoperated.

WILLIS McKEE.

